Many components of a turbine, such as the turbine blades, have an operational life beyond which maintenance or replacement is required An important factor in determining the operational life of turbine blades is the creep rupture life that is calculated for the turbine blades. The calculation of creep rupture life is dependent on several parameters and includes predictions for the mechanical stress levels and temperature that the turbine blades will be exposed to during operation and the duration of the stress levels and temperature. Alternatively, a turbine blade may be one-time tested under specific operating conditions to establish the parameters for determining operational life.
However, the actual operating conditions that the turbine blades are exposed to, such as the temperature, may vary significantly from the parameters initially used to calculate creep rupture life or test the turbine blades Further, it is difficult to inspect the blades to determine how much creep exists when the turbine is assembled and in operation
As a result, the turbine blades are replaced based on a conservative calculation for the creep rupture life in order to avoid catastrophic turbine failure. This can result in premature replacement of turbine blades thus increasing long term maintenance costs.